Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!crdgw1!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!haven!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Divide and C
Message-ID: <15636@smoke.brl.mil>
Date: 30 Mar 91 14:15:02 GMT
References: <639@taumet.com> <1991Mar29.163422.14672@uunet.uu.net> <1991Mar29.182919.20728@helios.physics.utoronto.ca>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 12

In article <1991Mar29.182919.20728@helios.physics.utoronto.ca> neufeld@aurora.physics.utoronto.ca (Christopher Neufeld) writes:
>   Are there compilers which go to the trouble of hardcoding something
>like this if they see division or multiplication by integer powers of
>two, or do they all get lazy and assume a math coprocessor?

Most compilers I've dealt with have optimized integer division and
multiplication by constant powers of two into shift instructions,
but not for floating-point operands.

By the way, it is not necessarily "lazy" to rely on an FPU for speed.
Anyone who has serious floating-point demands is going to get one
anyway.